It is known in the art to utilize heat shrink or shrink fit tool assemblies in industrial applications. The prior designs have utilized unitary chucks having an inner diameter slightly smaller than the exterior diameter of the shank of the cutting tool or other work piece. During use the tool chuck is heated, typically by means of induction heating, causing the chuck to expand a sufficient amount to allow the tool shank to be inserted within the chuck. The tool is then allowed to cool during which the thermal contraction of the chuck exerts a uniform pressure on the tool shank, allowing the chuck to shrink down around the tool shank to securely lock or hold the shank in place. It has long been recognized that these types of heat shrink tool assemblies provide an improvement in accuracy and rigidity over standard milling chucks or collet chucks.
In order to remove the tool, the chuck is re-heated to expand the opening. During the heating process the chuck transfers heat to the tool shank itself. The expanding tool shank can create problems with the removal of the tool from the chuck, even resulting in the tool remaining grasped by the chuck and requiring a significant force to remove the tool or a high temperature applied to the tool holder
Accordingly, there is a need for a heat shrink tool assembly that allows for the easy and quick removal of the tool from the chuck, especially in tools with small diameters. The thermal expansion is proportional to part dimension and the temperature difference between the tool and the chuck. In small tools, the removal may become an issue as the thermal expansion approaches the manufacturing tolerances.